Baby Gammy's biological father wanted access to donations

THE biological father of Gammy, the baby at the centre of a surrogacy dispute last year, is trying to access donations raised for the child's medical costs, a charity says.

The case made international headlines last year after convicted sex offender David Farnell and his wife Wendy Li abandoned their son in Thailand because he has Down syndrome and took only his twin sister back to Australia.

Gammy lives with his Thai surrogate mother, Pattaramon Chanbua, who depends on the money donated to charity to cover his medical costs.

The founder of the Hands Across The Water foundation, Peter Baines, told the ABC that Mr Farnell was now trying to access the money raised.

"It's perplexing. I don't understand it on any level," Mr Baines said.